Apparatus for producing safety paper



March 17, 1936. w, H, GROG'AN HAL 2,034,232

APPARATUS FOR PRODUCING SAFETY "PAPER Filed Sept. 15, 1933 Y FRANK C. LADD flagam' 9* ATT RNEYS 'MIPVENTORS I N vILL/AMH.alum/ml I Patented Mar. 17, 1936 UNITED STATES PATENT OFFICE APPARATUS FORPRODUCING SAFETY PAPER.

' William H. Grogan and Frank C. Ladd, Turners Falls, Mass, assignors to Keith Paper Company, Turners Falls, Mass.

, Massachusetts a corporation of Application September 13,1933, Serial No.689,218

3 Claims. (Cl. 92-40) This invention r'elatesto an apparatus and a method forincorporating in a paper webv bands of small tissue paper disks commercially known as planchets. These small disks when incorpo rated into the paper stock during its formation may be practically invisible as long as the paper is viewed in the ordinary manner by reflected light. They are, however, clearly visible "by transmitted light. If any attempt is made to alter, by erasure or chemical means, writing which overiles these disks they will be rendered abnorgeneral purpose in which a minimum of dismally distinct and willmake the fact or altera-- tion clearly apparent.

One object of this invention is to provide an improved apparatus for forming commercially webs of paper having one or more lines of planchets incorporated in the body of the web during its formation. A further object is to provide an apparatus and a method for handling the planchets and depositing them on a partially formed web in such a manner as to insure substantially even distribution of the planchets and to provide for the incorporation of the planchets into'the web with the planes of the individual disks all lying in the plane of the web. A further-object is to provide a method and-an apparatus for this turbance of the partially formed web will be created in the operation'of applying the planch ets. A further object is to provide a method and an apparatus by which the planchets will be embedded in the material of the web without causing any abrupt transition of character or oi ordinary appearance in the web stock on either side of or in the planchet band. Additional objects will appear from the following description and claims.

Referring to the drawing:

Fig. 1 is a diagrammatic view of an apparatus constructed in accordance with' our invention;-

Fig. 2 is a detail plan view of a portion of the apparatus shown in Fig. l; and

- Fig. 3 is'a detail elevation of one of the parts.

The present invention is preferably carried-out by adding the planchets to the paper stock during the formation of a webupon the wire of a Fourdrinier machine. Since Fourdrinier machines are standard in the paperm'aking art the Fourdrinierwire ID has been indicated diagrammatically only. The paper stock out of which the web is formed flows onto the moving wire from a head box II, and passes under a slice bar II by which irregularities in the thickness of the web are prevented. At a point preferably just beyond the slice bar a plurality of ducts or pipes l3 are provided, leading from a tank l4 extending across the wire. These ducts l3 terminate at a point, just above thepartially formed web on the wire and are given such an inclination that the stock flowing from them travels when it meets the web with substantially the same speed as the latter. As will be explained more fully below, the tank H is supplied with dilute stock in which a large number of planchets are intimately mixed. As the planchets are carried down the ducts l3 they encounter the as yet unmatted paper stock on the wire l0 and become incorporated with it as the web becomes more and more compact in its travel along the wire.

In commercial practice we have found that a properinter-mixture of the planchets with the paper stock on the wire can be controlled by certain precautions in the manner of preparation of the stock mixture in which'the planchets are floated and in the manner in which this stock mixture is handled during its passage from the supply tanks to the surface of the partially formed web. In the first place, inorder to avoid the formation of abrupt hinge lines in the paper web and to insure that the surface appearance of the planchets when embedded in the web will resemble the web itself rather than the paper out of which the planchets were cut, it is necessary to have the stock mixture possess characteristics similar to that possessed by the stock outof which the web is formed. Practically this result can be accomplished best by the-use, as a floating medium for the planchets, of the so-called white water which drains from the Fourdrinier wire. Since the white water contains mainly short fibers along with the chemicals which were pres ent in the original stock and since the fiber content of the white water would be diminished by repeated passing through the wire, it is generally desirable to add from time to time a certain additional amount of shortfibers to the white water when it is used for this purpose.

In the drawing a trayl5 has been shown conventionally as collecting the white waterfrom underneath the Fourdrinier wire. A pipe I6 con;- I nects this tray witha tank 11 from which the white water is normally taken off for use in otherparts of the paper making process by a pipe I8; We have provided an additional pipe 19 leading from the tank ll-to a pump 20 by which any desired quantity of the white water may be elevated and 3| provided with valves 32 and 33 lead from the lower portions of these tanks into a common pipe 34 which is shown as being directed into a tank 35 at a lower level. A pipe 36 leading from this tank in its upper portion leads to a pump 31 by which excessmaterialfrom the tank 35 may be returned to the pipe 2|. By this means a constant head can be maintained in the tank 35 at the level chosen for the pipe 36.

One or more pipes 40, each having a regulating valve 4| located in it, lead from the tank 35 to the tank M. It will be observed that with the system of piping described an adequate hydraulichead is maintained at all points toinsure proper delivery of the stock, but that the head is broken up so that the velocity of the stock will not be excessive at the time it reaches. the wire. In particular the level in the tank II is preferably kept low and the tank itself is located not very far above the surface of the wire 10. To'still further reduce the velocity 'ofthe stock as it reaches the wire the ducts ll are preferably made serpentine in form as is bestshown in Fig. 2.

Provision is also preferably made for agitating the planchet bearing stock in each of the tanks so that the planchets will be maintained in a substantially uniform state of suspension. For this purpose perforated pipes 45 are preferably located in the lower portions of each of the tanks 26, 21, and 3B. and are connected to a suitable compressed air supply. The bubbling of air through the tanks constantly agitates the stock so that any settling of theplanchets is im-, 'possible. The capacity of the tank [4 is relatively.

small so that direct agitation is generally unnecessaryand is generally undesirableon account of the tendency towards uneven discharge which it produces. f A suflicient degree of agitation for this tank is usually obtained by the constant movement of the stock as it emerges from the pipe 40. In case a large number of bands of planchets are to be applied to the web it is de sirable in order to secure uniform distribution that several pipes" be used spaced apart along the length of the tank in .accordance with the spacing of the pipes It. The pipes 40 may, in that event, be provided with separate controlling valves to insure evenness of flow, and the tank I provided with partitions l6. In order to insure an even flow of the planchet suspension from the pipes 40 to the final delivery ducts 13, the tank I4 is preferably provided with baflies 41 not quite reaching, the bottom of the tank, through one of which the pipes ,40 extend. The delivery ducts I 3 are bent upwardly as shown at ",between the baiiies. By this means a very even flow. through the ducts I I is obtained while preserving enough upward flow in the tank to keep the planchets always in suspension. The ends of ducts l3, which are preferably in pipe form, may be beveled oil as at II (Fig. 3) with the terminal portion preferably somewhat extended and flattened to form a delivery lip ll.

"The end portion of each pipe II, or the lip if used, is positioned close to the traveling partially formed web, preferably just clearing the still soft stock so that no disturbance of the latter will be produced.

It will be understood from the above description that the planchets are kept in a constant state of agitation in a stock mixture having sufflcient correspondence to the stock on the wire so that no abrupt line is formed at the edges of the planchetbands. The planchets will automatically arrange themselves in the plane of the web as they glide down the plates is, lying at first upon the top of the partially formed web, then becoming incorporated in it during its travel along the wire and during the further condensation of the web on the felts and between the press rolls.

Any agitation due to the addition of the planchets and their carrying medium is substantially eliminated The apparatus has been shown in diagrammatic form as the design of many of the specific units is not of importance. Changes in the structure and arrangement of the parts can obviously be made to adapt the invention to differentinstallations without departing from the invention as described in the following claims.

We claim: v 1. In an apparatus for incorporating planchets in a paper web during its formation upon a Fourdrinier wire, a collecting tankfor white water, a pair of storage tanks, means for delivering the white water from the collecting tank alter natively into one or the other of the storage tanks, a third storage tank, means for delivering the liquid from 'either of the first two storage tanks to the third storage tank, a pipe leading from said third storage tank at an intermediate elevation thereof, means fordelivering liquid from said pipe to the first two storage tanks to thereby preserve a constant level in the third 5 storage tank. means for agitating the liquidin each of the storage tanks, a delivering tank ex tending across a Fourdrinier wire, one, or more ducts leading from said delivering tank in a sinuous path to a point above the partially formed web on the wire, and one or more pipes leading from the third tank.

2. Anlapparatus for incorporating planchets into a paper web during its formation on a Fourdrinier wire which comprises a tank, a pipe extending upwardly to an intermediate elevation of said tank and leading to a point closely adjacent the paper stock on the wire, bailiing means within the tank extending to a point below the opening to the pipe, and means for supplyingto said tank below the baiile planchets ina substorage tank to said delivering stantialiy uniform state of suspension and in regulable quantity.

3. An apparatus for incorporating planchets into a paper web during its formation on a Fourdrinier wire which comprises a tank, a pipe extending upwardly to an intermediate elevation of said tank and leading to a point closely adjacent the paper stock on the wire, the end of the pipe adjacent the paper stock being cut away to provide an open distributing portion from which the planchets flow onto the stock, bailling means within point below the opening to the pipe. and means for supplying to said tank below the baiiie planchets in a substantially uniform state of suspension and in regulable quantity.

WILLIAM-I. oaooan. manganese.

the tank extending to a 

